Reducing Supplemental Lighting Costs in Orchid Production
Many orchids follow a unique photosynthetic pathway in which CO₂ is absorbed at night and stored as malate. During the day, the plants rely on stored malate for photosynthesis. Once the plant depletes its malate store, photosynthesis plummets. This transition point can shift daily depending on conditions, making it difficult for growers to predict when a plant has insufficient malate or CO₂ and intervene effectively. If growers don’t respond quickly enough to actual plant demand, they waste lighting and CO₂, and reduce crop uniformity.
To overcome this challenge, Gardin (a UK-based agritech company that uses AI-powered optical sensors to measure plant physiology in real-time) recently used its non-invasive, chlorophyll fluorescence sensors to measure photosynthetic efficiency to detect malate depletion, CO₂ limitation, and light stress in real-time. This is designed to enable growers to adjust CO₂ dosing, lighting, and climate conditions at the onset of malate depletion. Gardin’s autonomous system monitors photosynthetic performance, providing crop-representative measurements that allow data-driven decisions at scale.
Timing of Malate Depletion Depends on Climate
In an independent research trial conducted at Plant Lighting, Gardin measured the photosynthetic efficiency of two orchid cultivars (Leeds and Freeride) under solar simulating lamps and LED spectrum. Measurements were taken during two temperature phases: 29°C (growth phase) and 21°C (chilling phase), and were validated using a research-grade reference instrument. A day-length of 15 hours was used, consisting of 13 hours at 150 μmol/m²/s and two 1-hour periods at 50 μmol/m²/s, split between the beginning and end of the day.
Gardin repeatedly detected declines in photosynthetic efficiency, with the timing varying between temperature, light source, and cultivar, with the largest decline observed under LED lighting. At 29°C, efficiency begins to drop after eight hours of LED light for both cultivars, compared with nine hours under sunlight. At 21°C, efficiency declines after seven hours across all treatments except Freeride under sunlight, which maintains efficiency until nine hours.
Orchid Production Optimization Saves Energy Costs
Many commercial orchid growers already dynamically adjust their supplemental lighting to a target daily light integral (DLI), especially during the darker months. Results from the case study showed that the timing of malate depletion varied with cultivar, temperature, and light source. As a result, even with a good DLI target, on some days high intensity lighting may still continue after malate depletion.
If you assume up to two hours per day where lighting dimmed by 50% once malate depletion is detected (with an LED efficacy of 2.0 μmol/J), over peak winter (16 weeks) this yields energy savings of up to 8.4 kWh m⁻². Equally, growers can save energy costs during the shoulder season, when some lighting is still applied to hit DLI targets. In this period, assuming up to one hour per day of a 50% dimming over the combined eight-week shoulder season, this can add up to a further 2.1 kWh m⁻².
Real-time detection of crassulacean acid metabolism (CAM) malate depletion enables growers to further optimize their production strategy. By dimming supplemental lighting when malate depletion is detected (during winter and shoulder seasons) can generate annual savings of up to €21,000/Ha/y. This highlights the value of monitoring CAM malate depletion in real-time, on top of an existing DLI strategy.
You can find the full case study here.
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